Researchers found that the number of prescription-drug users had risen from two decades ago, when about four in 10 Americans had at least one prescription.

Several factors contributed to the rise, the report said. New and better drugs are constantly hitting the market, more people have health insurance that covers prescriptions, and drugmakers are spending more on marketing. Most of the marketing focuses on doctors, but the report noted drug companies collectively spent $4.2 billion on direct-to-consumer advertising in 2005 - more than triple what they spent a decade before.

Perhaps the biggest change came in use of antidepressants: The group using these drugs increased more than fourfold from 1988 to 1994 and 2007 to 2010. Use rose in all age groups and both genders but was most common among middle-age women.

Cardiovascular drugs that control blood pressure and treat heart and kidney disease were the most common prescriptions for adults, followed by cholesterol-lowering drugs and acid-reflux treatments.

For children, remedies for asthma and allergies edged out antibiotics on the most-prescribed list. Antibiotics were, by far, the most common prescription for children from 1988 to 1994, but physicians have scaled back in recent efforts to prevent bacteria from becoming drug-resistant.